DESCRIPTION: The underlying goal of this research program to identify the molecular mechanisms underlying acquired resistance to the platinum drugs. The investigator has demonstrated that selection for the cisplatin-resistant phenotype results in cross resistance to a family of metalloids including arsenite, antimonite, selenite and tellurite (RASP phenotype). This pattern of cross resistance is mediated by an ATP dependent membrane export pump coded for by the arsA and arsB genes in bacteria. The hypothesis is that the human homolog of the arsA (harsA) plays a role in the resistance to DDP CBDCA in mammalian cells. Using degenerate primers a fragment of the human arsA gene was cloned and used to isolate both cDNA and genomic clones of this novel gene from lambda-based and P1-based libraries respectively. The specific aims are to compare the expression, sequence and structure of this gene in human ovarian carcinoma 2008 cells and sublines selected with DDP, arsenite and antimonite for expression of the RASP phenotype and their revertant., to determine whether expression of harsA regulates sensitivity to DDP, arsenite and antimonite, to identify the location of the gene in the human genome and characterize its genomic structure, to examine the differences in expression harsA in various human tissues and whether expression of i induced by cisplatin or metalloids themselves or by signal transduction pathways known to influence cisplatin sensitivity, and finally to begin characterization of the gene product by preparing pure protein, generating antibodies and measuring the level and subcellular location of the harsA gene product in drug sensitive and RASP phenotype cells.